Homemade slime craze raises safety concerns over 'toxic' ingredients

The homemade slime experiment has become a huge playground trend in recent years - but now experts are warning that one of the key ingredients could be dangerous if used improperly.

The popular balls of colourful slime, which can be made at home or bought online, often contain borax, a chemical which can be toxic if not safely diluted, particularly if it gets into the eyes or lungs.

The substance can even reportedly have an impact on fertility: the EU's European Chemicals Agency (ECHA) states that borax can be 'toxic to reproduction', releasing a hazard alert explaining: 'This substance may damage fertility or the unborn child and causes serious eye irritation.'

Steve Jones, director of the schools' science advisory service, told the Daily Mail: 'Making the slime is what we're most concerned about, because you're trying to limit the amount of dust you raise. If you splash it around your kitchen willy-nilly you're exposing yourself to something classified as toxic.'

According to the paper's report, chemistry teachers are advised to dilute borax in solution to a level of 1g of borax in 20ml of water to make it safe to use in classrooms.

The sensory nature of slime means that it's captured the attention of children of all ages

There are many recipes online for slime made without borax, usually consisting of ingredients such as glue, cornstarch, food colouring and water, which may be preferable for parents concerned about the potential hazards of the chemical.

Duncan McMillan, from the Royal Society of Chemistry, added: 'The polymer slime experiment is designed to be carried out by or with the supervision of a qualified teacher or responsible adult. And while it's fun for children, as with any experiment it's important to take health and safety seriously.'